The present disclosure relates generally to extraction processes for naturally-occurring compounds. In particular, extraction processes and methods for cannabinoids and terpenes are described.
Cannabis is a genus of plants that include three species, Cannabis sativa, Cannabis indica, and Cannabis ruderalis. This genus has long been in use for its hemp fiber material, as milk, seeds and oils, for medicinal purposes, and for recreational use. As more regions approve the use of cannabis for both medicinal and recreational use, more cannabis-derived products are being produced than ever before. Many of these cannabis-derived products utilize the primary psychoactive component of the Cannabis plant, tetrahydrocannabinol (THC). Cannabis plants initially contain tetrahydrocannabinolic acid (THC-A) and cannabidiolic acid (CBD-A); these compounds break down to THC and cannabindiol (CBD) when exposed to UV light and/or heat. THC belongs to the larger family of cannabinoids. CBD is a non-psychoactive cannabinoid that is used in medicinal preparations. The methods disclosed within this application can be applied to any of these compounds mentioned.
Currently, the primary method for extracting from Cannabis plants involves the use of small hydrocarbons such as propane, butane, and hexane. Solvents such as propane, butane, and hexane are highly toxic. Propane is a flammable gas, often used in cooking stoves, and is harmful if its vapors are inhaled or swallowed. Butane is also an organic compound often used in fuel products and refrigerants. Inhalation of butane fumes can cause a range of undesirable effects such as asphyxiation and ventricular fibrillation. Similarly, hexane also causes a host of negative side effects (e.g. nausea, vertigo, intestinal irritation, and CNS effects). Further hazards include more, butane-related explosions and fires when the would-be home chemist attempts to make butane honey oil (BHO).
Butane also has a propensity to extract waxes and other undesired hydrophobic compounds that either remain or require further purification processes to remove from solutions containing cannabinoids. In one embodiment, in order to remove waxes, butane is first allowed to evaporate and the resulting concentrate is re-dissolved in an alcohol-based solution such as isopropyl alcohol or ethanol, and allowed to freeze at −20 degrees Celsius for up to 48 hours to selectively precipitate the waxes out of solution. The resulting mixture then must be vacuum filtered to separate out the precipitated waxes, the alcohol then must be removed from the concentrate through distillation, and finally the mixture purged in a vacuum to reduce the levels of residual solvent to acceptable levels.
Other methods of extracting cannabinoids include the use of FDA “food grade” solvents, such as ethyl alcohol, glycerin, and propylene glycol. While these compounds are safer than the alkanes previously mentioned (e.g. butane, propane and hexane), their properties make it laborious, time-consuming, and difficult to concentrate and purify cannabinoids from the resultant extracts. For instance, water is often a significant portion of ethyl alcohol, some times as much as 60%. The excess of water results in aqueous-soluble impurities such as chlorophyll, flavonoids, and other undesired compounds becoming part of the extract. These impurities can be very challenging to separate from the desired cannabinoid compound. In order to remove these impurities, the unpurified mixture often has to be dissolved in toxic solvents such as chloroform and then subjected to numerous extraction and chromatographic separations. The use of toxic solvents does not give the impression of “clean medicine” or “food grade” compounds. Finally, the use of these existing extraction techniques and purification methods is likely to be unprofitable in a scaled up production due to costs associated with more expensive laboratory equipment and training individuals to perform such tasks safely and without impacting the environment.
In addition to cannabinoids, similar compounds such as terpenes would also benefits from less toxic methods of extraction. Terpenes are resins and volatile compounds found in many kinds of plants including conifers and flowering plants. Terpenes are useful in the food, cosmetic, pharmaceutical and biotechnology industries.
Thus, there exists a need for cannabinoid and/or terpene extraction processes that improve upon and advance the design of known extraction processes. Examples of new and useful cannabinoid and terpene extraction processes relevant to the needs existing in the field are discussed below.
Disclosure addressing one or more of the identified existing needs is provided in the detailed description below. Examples of references relevant to cannabinoid extraction techniques include U.S. Patent References: U.S. Pat. No. 6,403,126 to Webster (“Webster”), U.S. Pat. No. 8,530,679 to Bhatarah (“Bhatarah”), and U.S. Pat. No. 6,365,416 to Elsohly (“Elsohly”).
The method described in Webster extracts cannabinoids using organic solvents. These solvents include petroleum-derived hydrocarbons such as toluene and trimethylpentane or alcohol such as ethanol or dicholormethane, a low molecular weight chlorinated hydrocarbon. Toluene, trimethylpentane, and dichloromethane are all toxic and flammable. Furthermore, Webster describes extracting cannabinoid using subcritical water and supercritical fluid such as carbon dioxide. While these latter techniques involve non-harmful compounds, performing extractions with supercritical fluids and subcritical water requires more sophisticated equipment as well as expertise to perform compared to the simple extraction technique described in this application.
The process described in Bhatarah also uses organic solvents for extracting the cannabinoids. The solvents specifically pointed out are n-propane, isopropane, cyclopropane, n-butane, isobutane and isobutylene. As mentioned earlier, butane and its counterparts, are highly flammable and thus dangerous. Furthermore, residual butane left after the extraction process can be harmful to the user. Additionally, butane and like compounds also have the tendency to extract waxes and other undesirable hydrophobic compounds which may need to be removed with additional steps.
The method described in Elsohly also uses organic solvents. The organic solvents mentioned are hexane, heptane or iso-octane. Similar to the solvents mentioned earlier, these compounds are not fit for human consumption and could create adverse effects if ingested. Furthermore, the method described in Elsohly requires both purification using column chromatography and large-scale HPLC. Both of these methods require expensive lab ware and purification systems. Finally, the solvents used in both of the purification steps are also toxic and not fit for human consumption.